When Mexican President Felipe Calderón sent his army after the country’s powerful drug cartels six years ago, we all understood the rationales. For starters, Calderón had won the 2006 presidential election by a razor-thin margin, about half a percentage point, and he needed to establish a firmer presence in Los Pinos, the Mexico City presidential residence, with a bold act of authority. Taking on the cartels, whose ghastly violence was overrunning the northern border and numerous large cities, was certainly a legitimate move. So was deploying 50,000 of Mexico’s troops instead of relying on its cops: Calderón realized that Mexican police were too hopelessly corrupt and incompetent to do the job.

But if Calderón’s call was gutsy, much of it was as ill conceived as taking a baseball bat to a hornet’s nest without knowing what you’re going to do with the hornets.

Granted, the military campaign has captured or killed some key drug capos and made some impressive drug busts. But the cartels aren’t that much weaker than they were six years ago — narcos this month torched the warehouses of one of Mexico’s largest food-and-beverage companies, and this week they dropped leaflets from planes over Sinaloa state condemning the government — and in the meantime some 50,000 Mexicans have been murdered, including 49 decapitated victims recently dumped on a northern highway. While putting soldiers on the streets might have provided some short-term relief, the fact remains that in the long run, soldiers make lousy antidrug agents — armies don’t bring down organized crime, professional police do — and the longer they’re kept in that role, the more problems you’re going to have.

Not surprisingly, the Mexican military has a lot of problems right now. The monstrous cartels themselves are certainly to blame for Mexico’s narcohorrors. But groups like the New York City–based Human Rights Watch have also accused the military of widespread drug-war abuses, including the torture, disappearance or killing of hundreds if not thousands of innocent civilians. On top of that, in May, some of the military’s top brass were arrested — including an army general who until 2008 had been the No. 2 official in the Defense Ministry — apparently for being in the pocket of one of Mexico’s leading drug-trafficking organizations, the Beltran-Leyva cartel.

The arrested men — army General Tomás Angeles and three other high-ranking officers — deny the charge. Many Mexicans are asking whether politics played a role in their detentions since Angeles, who had hoped to become Mexico’s Defense Secretary, is reportedly a critic of Calderón’s drug-war strategy and is said to favor the candidate of the Institutional Revolutionary Party (PRI), Enrique Peña Nieto, who holds a large lead in voter polls over the candidate of Calderón’s National Action Party (PAN) for the July 1 presidential election. (Mexico’s Attorney General has adamantly denied any political impetus.) Skeptics also say much of the evidence against Angeles that has been reported so far smacks of hearsay. Some in the Mexican media suggest the arrests are part of a power struggle inside the insulated armed forces. Others say Calderón is on the level when he insists, as he did this month, that his government simply “won’t tolerate illegal acts.”

Whatever the reasons, it’s hardly unprecedented to see a top Mexican military leader get collared for narcocorruption. This year, in fact, marks the 15th anniversary of one of the most shocking cases — the arrest (and later the conviction) of none other than Mexico’s then drug czar, army General Jesús Gutiérrez Rebollo, for being in the pay of Mexico’s top drug lord at the time, Amado Carrillo Fuentes. That crisis prompted then President Ernesto Zedillo to outright scrap Mexico’s federal drug-interdiction agency and start all over again; and if the charges against Angeles and the other officers are true, Mexicans are bound to experience a similar sinking feeling.

Now, as then, the only real remedy is to phase out Mexico’s reliance on the military and develop genuinely professional, investigative police forces. But that’s a harder task than simply calling out the cavalry — and Mexico, despite Calderón’s efforts to also push police and judicial reform through Congress, still doesn’t look all that interested in tackling the harder task.

Fairly or not, the military arrests, especially if Angeles and the others are found guilty, are for Mexicans a dismal punctuation mark to the past six years — and possibly to Calderón’s legacy. (By law he is limited to one six-year term.) Nor will they do much to reassure an already skeptical Washington, which has committed — hesitantly — some $1.5 billion to Mexican-drug-war aid.

At the same time, the arrests seem to vindicate Carlos Pascual, the former U.S. ambassador to Mexico who was forced to resign last year after Calderón blew a fuse about WikiLeaked diplomatic cables that show Pascual casting doubts on the Mexican military’s reliability in the drug war. One of Pascual’s chief concerns was the brass’s commitment to taking down the Beltran-Leyva gang.